1. Technical Field
The present invention relates to a fuel cell system using a fuel cell as a power source and its operating method.
2. Background Art
In recent years, power consumption of a portable apparatus represented by a portable telephone has been increased more and more in accordance with high function formation of the apparatus, and an increase in a capacity of a power source poses a serious problem. Recently, attention is attracted to a fuel cell as a small-sized energy source having a high energy density. According to the fuel cell, an electrolyte is interposed by two kinds of electric poles. Electricity is generated by oxidizing a fuel of hydrogen, methanol or the like by a fuel pole and deoxidizing oxygen in the atmosphere by an oxygen pole. Among fuel cells, a solid polymer type fuel cell can generate power at a vicinity of room temperature, provided with a high output density and can be downsized and therefore, application thereof as a power source for a portable apparatus is expected.
However, after stopping power generation by the solid polymer type fuel cell, when a fuel remaining at an inside of the fuel cell is left without being removed from the fuel cell, various problems are posed.
For example, when methanol is used as a fuel, there pose problems of a deterioration of an electrolyte film by swelling the electrolyte film, consumption of the fuel by crossover of the methanol fuel and the like, and when hydrogen is used as a fuel, there pose problems of leakage of hydrogen, a danger of explosion in accordance with leakage of hydrogen and the like.
With regard to the problems, there is known a method of removing the fuel at inside of the fuel cell by generating power by the fuel cell by the fuel remaining at the inside of the fuel cell and consuming power by a load of a heater, a resistor or the like.
However, according to the method, there pose problems that a rate of efficiently utilizing the fuel is reduced and the energy density of the fuel cell system is reduced.